1. Field of the Invention
The present invention generally relates to a loudspeaker having a plurality of flat panel speakers or planar magnetic transducers. More particularly, the present invention relates to a surface loudspeaker array using a plurality of full-range flat panel or planar magnetic transducers that are mounted closely together on either a flat or a curved surface to produce a substantially controlled sound dispersion in both the horizontal and vertical planes.
2. Background of the Invention
Designing audio systems for venues such as stadiums, auditoriums, or theme parks can be difficult. Most companies use traditional speakers arranged in line arrays for such professional applications. The individual speaker elements are typically designed as two- or three-way speaker boxes with direct radiating woofer sections and horn-loaded midrange and tweeter drivers.
Line arrays of speakers are used only infrequently in a straight-line or vertical column configuration, however, because a line array in straight-line configuration has a very narrow vertical sound dispersion. Thus, a line array in straight-line configuration covers a very limited space in the vertical plane. To increase the vertical coverage, the individual speakers in the line arrays are usually curved in the vertical direction, or “vertically splayed,” to achieve the desired sound dispersion angle.
The column of speakers is suspended in the air near the area where the sound is desired by various diverse rigging systems. The rigging systems connect the speaker boxes in a compact structure that curves adequately in the vertical plane to provide the desired vertical sound coverage. If the vertical splaying angle between individual speakers is too great, there will be a gap in the sound dispersion, so the vertical splaying angle between line array speaker boxes is usually no more than 5 degrees. A line array of typical speakers would require a vertically curved column of 16 speaker boxes to achieve 80 degrees of vertical coverage, but such an array is both extremely heavy and very expensive. It is therefore not a practical solution for the vast majority of venues.
To keep costs and weight low while still providing vertical sound coverage, the normal solution is to use shorter line arrays with smaller vertical coverage to cover the middle and rear of the venue, and to add separate fill speakers that are used to cover the front of the venue. Unfortunately, this solution produces distorted sound quality in portions of the venue.
Another difficulty with current line array systems particularly affects travelling productions that carry their own audio equipment, such as touring bands that play to large crowds in large venues. An enormous amount of audio equipment is necessary to fill the typical venues at which those travelling productions play with high quality, high volume sound. Thus, the travelling productions must carry with them trailer loads full of speakers, rigging systems, crossovers, computer and electronics equipment, cabling, and the crews who actually set up and remove the equipment. Those crews must spend hours setting up and testing the equipment before each show, and then additional hours after the show removing and storing the equipment.
Another problem with current line array systems involves the rigging systems used to connect the speaker boxes in a structure that curves adequately in the vertical plane to provide the desired vertical sound coverage. Although traditional rigging systems are able to control the vertical splaying angle between individual speakers or rows of speakers, such systems, particularly for larger arrays, can be extremely complicated, difficult to deploy, heavy, and expensive.
An additional problem is that in situations where wider than nominal horizontal sound coverage is desired, simply adding another line array close to the first array is usually not possible due to large phase problems and destructive interference from arrays closely spaced together in the horizontal plane. To avoid those problems, frequently two arrays must be widely separated, which can be extremely difficult or impossible in many situations because of space restrictions.